Kia Cerato: Lower sill and rear quarter panel lower edge corrosion

The Cerato LD has thin-gauge steel at the lower door sill box section seam and the lower 100-150 mm of the rear quarter panel where factory anti-corrosion wax cavity injection coverage was inconsistent across production years. Moisture and road debris accumulate in the closed sill section via drain holes and seam gaps, and the factory seam sealer degrades over time. Corrosion initiates from inside the closed section and is invisible externally until a paint blister appears, at which point significant metal thickness has already been consumed from within. Rear quarter corrosion typically originates at the lowest pinch weld seam and migrates upward into the wheel arch lip. Vehicles imported from Japan frequently show hidden structural rust concealed under body filler applied before export.

• Paint blistering along lower sill between front and rear door edges
• Bubbling or lifting paint at rear quarter panel base immediately above sill line
• Hollow or dull sound when tapping lower sill with knuckle rather than solid ring
• Rust staining or dark seepage visible at lower door jamb seam

1. 1

   Run a magnet along the lower sill and rear quarter — presence of filler reduces magnetic pull measurably.

2. 2

   Inspect door jamb seams with a torch for rust bleeding or seam sealer cracking.

3. 3

   Lift or probe the rubber sill trim strip to expose seam sealer condition underneath.

4. 4

   Check inner rear wheel arch panel for perforation or rust patches visible from inside the boot.

Parts involved: Body corrosion.

$600 to $2,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has any rust repair or body work been done to the sills or rear quarter panels?”
• “Was this vehicle imported from Japan and if so has it been inspected by a rust specialist?”
• “Has the car experienced water ingress or flood damage at any point?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.